U.S. patent number 8,157,526 [Application Number 11/918,302] was granted by the patent office on 2012-04-17 for component having a film cooling hole.
This patent grant is currently assigned to Siemens Aktiengesellschaft. Invention is credited to Thomas Beck, Silke Settegast.
United States Patent |
8,157,526 |
Beck , et al. |
April 17, 2012 |
Component having a film cooling hole
Abstract
Conventionally coated components with film cooling holes are
known, comprising a diffuser, extending through the layers into the
substrate. According to the invention, the component is embodied
such that the whole diffuser is largely arranged in the layer.
Inventors: |
Beck; Thomas (Panketal,
DE), Settegast; Silke (Berlin, DE) |
Assignee: |
Siemens Aktiengesellschaft
(Munich, DE)
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Family
ID: |
35134387 |
Appl.
No.: |
11/918,302 |
Filed: |
March 16, 2006 |
PCT
Filed: |
March 16, 2006 |
PCT No.: |
PCT/EP2006/060794 |
371(c)(1),(2),(4) Date: |
October 11, 2007 |
PCT
Pub. No.: |
WO2006/108749 |
PCT
Pub. Date: |
October 19, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090067998 A1 |
Mar 12, 2009 |
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Foreign Application Priority Data
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Apr 12, 2005 [EP] |
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05007993 |
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Current U.S.
Class: |
416/97R;
416/241R |
Current CPC
Class: |
F01D
5/186 (20130101); F01D 5/286 (20130101); F01D
5/288 (20130101); F23R 3/04 (20130101); F05D
2300/21 (20130101); Y02T 50/6765 (20180501); F05D
2250/324 (20130101); F05D 2300/13 (20130101); F05D
2230/90 (20130101); F23R 2900/03042 (20130101); Y02T
50/676 (20130101); Y02T 50/60 (20130101); Y02T
50/67 (20130101) |
Current International
Class: |
F01D
5/18 (20060101) |
Field of
Search: |
;416/97A,97R,241R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0228338 |
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Jul 1987 |
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EP |
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0412397 |
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Feb 1991 |
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EP |
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0486489 |
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May 1992 |
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EP |
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0786017 |
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Jul 1997 |
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EP |
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0892090 |
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Jan 1999 |
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EP |
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0 950 463 |
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Oct 1999 |
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EP |
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1 043 480 |
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Oct 2000 |
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EP |
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1076107 |
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Feb 2001 |
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EP |
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1091090 |
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Apr 2001 |
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EP |
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1204776 |
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May 2002 |
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EP |
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1306454 |
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May 2003 |
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EP |
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1319729 |
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Jun 2003 |
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EP |
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1350860 |
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Oct 2003 |
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EP |
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Primary Examiner: Look; Edward
Assistant Examiner: White; Dwayne J
Claims
The invention claimed is:
1. A component having a film cooling hole, comprising: a component
substrate; and a layer arranged on the substrate where the film
cooling hole comprises a diffuser in an outer region and a hot gas
flows over the film cooling hole in an overflow direction, the film
cooling hole comprising a lower part, and the diffuser adjoins the
lower part as part of the film cooling hole and wherein, the
diffuser is substantially arranged in the layer, an overall length
of the diffuser as measured along a normal to the outer surface of
the layer includes a first length which is completely arranged in
an overall coating thickness and a second length which is arranged
in the substrate whereby the first length is significantly less
than the second length, the diffuser widens in the plane of the
outer surface of the layer in an overflow direction at an angle to
the overflow direction transversely to the overflow direction, the
outlet opening of the film cooling hole comprises a leading edge
and a trailing edge in the overflow direction and the diffuser
widens in the plane of the outlet opening starting from the leading
edge, so that the diffuser is shaped trapezoidally in the plane of
the outer surface.
2. The component as claimed in claim 1, wherein the substrate
comprises an outer surface, and the film cooling hole extends
between an angle of 30.degree.-45.degree. to the outer surface in
the layer.
3. The component as claimed in claim 1, wherein a medium flows
through the film cooling hole in an outflow direction, the film
cooling hole comprises a lower part, the diffuser adjoins the lower
part as part of the film cooling hole and in the outflow direction
has a cross section widening perpendicular to the outflow
direction, the cross section of the diffuser widening in particular
only in the overflow direction.
4. The component as claimed in claim 3, wherein the diffuser has a
longitudinal length in the plane of the outer surface in the
overflow direction equal to 3 mm, and the broadest transverse
length perpendicularly to the longitudinal length is at most 10
mm.
5. The component as claimed in claim 1, wherein in that a medium
flows through the film cooling hole in an outflow direction, in
that the film cooling hole comprises a lower part, in that the
diffuser adjoins the lower part as part of the film cooling hole,
in that a contour line along the contour of the lower part extends
parallel to the outflow direction, a diffuser line extends on the
inner side of the diffuser, which is a projection of the overflow
direction onto the inner face of an appendage of the diffuser, and
the diffuser line makes an angle of 10.degree. with the contour
line.
6. The component as claimed in claim 1, wherein a hot gas flows
over the film cooling hole in an overflow direction, a medium flows
through the film cooling hole in an outflow direction, the film
cooling hole comprises a lower part, the diffuser adjoins the lower
part as part of the film cooling hole and in the outflow direction
has a cross section widening perpendicular to the outflow
direction, the area of the diffuser as seen in the overflow
direction at the level of the surface is arranged substantially
behind the film cooling hole.
7. The component as claimed in claim 1, wherein an angle between
the overflow direction and a lateral delimiting line of the
appendage of the diffuser in the plane of the surface is
10.degree..
8. The component as claimed in claim 1, wherein the layer comprises
two layers, an outer layer and an intermediate layer, and wherein
the outer layer is applied on the intermediate layer.
9. The component as claimed in claim 8, wherein the intermediate
layer consists of an MCrAlX type alloy, and the outer layer
constitutes a ceramic thermal insulation layer.
10. The component as claimed in claim 1, wherein the component is a
steam or gas turbine component.
11. The component as claimed in claim 10, wherein the steam or gas
turbine component is a turbine blade or a heat shield element.
12. A component having a film cooling hole, comprising: a component
substrate; and a layer arranged on the substrate where the film
cooling hole comprises a diffuser in an outer region and a hot gas
flows over the film cooling hole in an overflow direction, the film
cooling hole comprising a lower part, and the diffuser adjoins the
lower part as part of the film cooling hole and wherein, the
diffuser is substantially arranged in the layer, the overall
coating thickness is 60% of an the overall length of the diffuser
as measured along a normal to the outer surface of the layer
includes a first length which is completely arranged in an overall
coating thickness and a second length which is arranged in the
substrate whereby the first length is significantly less than the
second length, the diffuser widens in the plane of the outer
surface of the layer in an the overflow direction at an angle to
the overflow direction transversely to the overflow direction, the
outlet opening of the film cooling hole comprises a leading edge
and a trailing edge in the overflow direction and the diffuser
widens in the plane of the outlet opening starting from the leading
edge, so that the diffuser is shaped trapezoidally in the plane of
the outer surface, wherein the diffuser consists of a continuation
of the contour of the lower part and an appendage, and only the
appendage of the diffuser widens toward the outer surface so that
it is shaped trapezoidally in the outer surface.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is the US National Stage of International
Application No. PCT/EP2006/060794, filed Mar. 16, 2006 and claims
the benefit thereof. The International Application claims the
benefits of European application No. 05007993.8 filed Apr. 12,
2005, both of the applications are incorporated by reference herein
in their entirety.
FIELD OF INVENTION
The invention relates to a component having a film cooling hole
according to the claims.
BACKGROUND OF THE INVENTION
Components for applications at high temperatures consist of a
superalloy with additional protection against oxidation, corrosion
and high temperatures. To this end, the substrate of the component
comprises a corrosion protection layer on which, for example, an
outer ceramic thermal insulation layer is also applied.
Through-holes, out of which a coolant flows on the outer surface
and contributes to the film cooling, are also made in the substrate
and the layers for additional cooling. The film cooling hole is
widened in the vicinity of the outer surface to form a so-called
diffuser. When newly producing a component having a film cooling
hole, problems arise since the diffuser must be made both through
the layers and for the most part in the substrate. During the
refurbishment of components, the problem is that the through-hole
is already present and the substrate needs to be recoated, so that
coating material must subsequently be removed from the diffuser
region in the through-hole.
U.S. Pat. No. 4,743,462 discloses a method for closing a film
cooling hole, in which a plug consisting of a pin and a spherical
head is inserted into the film cooling hole. A bell-shaped
indentation is thereby produced inside the coating. The indentation
does not serve as a diffuser, however, since it is symmetrically
designed.
The functionality of the head furthermore consists in the material
of the head evaporating during the coating. It is not therefore
possible to produce accurate, reproducible indentations for a
multiplicity of film cooling holes.
Similar symmetrical widening of a film cooling hole is disclosed in
FIG. 3 of U.S. Pat. No. 6,573,474.
EP 1 350 860 A1 discloses a method for masking a film cooling hole.
The material of the masking means is selected so that no coating
material is deposited there during the subsequent coating. An
accurate, reproducible shape of the indentations inside a layer
cannot be produced in this case. Furthermore, a diffuser is not
described here.
EP 1 091 090 A2 discloses a film cooling hole in which a groove is
made in the layer, so that the groove extends along a plurality of
film cooling holes. Neither the film cooling holes nor the groove
have a diffuser region.
U.S. Pat. No. 5,941,686 discloses a layer system, in which the
substrate is processed. A diffuser region is not disclosed.
EP 1 076 107 A1 discloses a method for masking film cooling holes
in which a plug, which protrudes from the hole, is respectively
produced in the film cooling hole. To this end air is blown through
the film cooling hole in a first step and a coating is applied, a
precursor for the plug to be produced subsequently being introduced
into the film cooling hole and into the coating. That part of the
plug which is arranged inside the temporary layer has its shape
determined by how strongly a medium is blown through the film
cooling hole and how the coating of the temporary layer is carried
out. The shape of that part of the plug which protrudes from the
hole is therefore not reproducible.
SUMMARY OF INVENTION
It is therefore an object of the invention to overcome this
problem.
The object is achieved by a component as claimed in the claims.
Further advantageous measures, which may arbitrarily be combined
with one another in an advantageous way, are listed in the
dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 6 show exemplary embodiments of a component according to
the invention having a film cooling hole,
FIGS. 7, 8 show a plan view of a film cooling hole according to the
invention,
FIGS. 9 to 13 show configurations of a film cooling hole,
FIG. 14 shows a turbine blade,
FIG. 15 shows a combustion chamber,
FIG. 16 shows a gas turbine.
DETAILED DESCRIPTION OF INVENTION
FIG. 1 shows a component 1, 120, 130, 138, 155 consisting of a
substrate 4 and a single outer layer 7.
Particularly for components 120, 130, 138, 155 for turbines, the
substrate 4 is a superalloy based on iron, nickel and/or cobalt.
The outer layer 7 is preferably a corrosion and/or oxidation layer
based on an MCrAlX alloy (FIG. 15).
It may however also be ceramic.
The substrate 4 and the layer 7 comprise at least one film cooling
hole 28 which, on the side 22 which is hot under operational
conditions of use, comprises a diffuser 13 which departs from the
e.g. cylindrical, square or generally speaking symmetrical contour
49 of the lower part 24 of the film cooling hole 28 near a cooling
reservoir 31 and increases in cross section.
The film cooling hole 28 thus consists of a lower part 24 and the
outer diffuser 13. The diffuser 13 has an outlet opening 58, over
which a hot gas flows in an overflow direction 37.
The diffuser 13 is formed from an imaginary extension 12 of the
contour 49 as far as the surface 25 and an appendage 14 (FIG. 2),
which adjoins one or more side faces of the extension 12.
In the cross-sectional view of FIG. 1, the appendage 14 preferably
has a wedge shape.
In the plane of the outer surface, the diffuser 13 thus does not
have rotational symmetry, the centroid of the asymmetric shape
being displaced in the overflow direction 37 from the centroid of
the symmetric shape of the contour 49.
Along the normal 27 to the outer surface 25, that cross-sectional
area of the film cooling hole 28 which is perpendicular to the
normal 27 becomes greater, i.e. the diffuser 13 is fully or
preferably partially designed with a funnel shape.
According to the invention, the diffuser 13 is arranged for the
most part inside the single layer 7, i.e. when the diffuser 13
extends with an overall length 19 into the depth along a normal 27
of the component 1 which is perpendicular to the outer surface 25
or perpendicular to the overflow direction 37, then there is a
substrate length 16 of the diffuser 13 which constitutes the
proportion of the diffuser 13 in the substrate 4. The substrate
length 16 is designed to be significantly less than the overall
length 19. The overall coating thickness 26 (here that of the layer
7) forms the remaining part of the overall length 19 of the
diffuser 13. The coating thickness 26 is at least 50%, preferably
at least 60% or at least 70%, in particular 80% or 90% of the
overall length 19.
As an alternative, the diffuser 13 may be arranged entirely in the
single layer 7 (FIG. 3, layer thickness 26=overall length 19).
In FIG. 4, there are two layers on the substrate 4.
These are in turn a corrosion and oxidation protection layer 7, on
which an outer ceramic thermal insulation layer 10 is also
applied.
As in FIG. 1, there are lengths 16, 19 of the diffuser 13, the
layer thickness 26 again constituting at least 50%, 60% or in
particular 70%, in particular 80% or 90% of the overall length
19.
The diffuser 13 may likewise be arranged entirely in the two layers
7, 10 (FIG. 5).
Correspondingly as for the two layers according to FIGS. 4, 5, this
also applies for three or more layers.
The fact that the diffuser 13 is arranged for the most part or
entirely in the layers 7, 10 provides advantages for refurbishing
the component 1, for example in respect of laser erosion or removal
of material, above the lower part 24, which covers the outlet
opening 58 after recoating of the component 1, specifically in that
the laser or other coating apparatus only needs to be adjusted for
the material of the layers 7, 10 and processing of the other
material, i.e. that of the substrate 4, does not need to be taken
into account.
FIG. 6 shows a cross section through a component 1 having a film
cooling hole 28.
The substrate 4 comprises an outer surface 43, on which the at
least one layer 7, 10 is applied.
The diffuser 13 is for example arranged for the most part
(according to FIGS. 1, 3, 4, 5) in the layer 7, 10, although it may
also exist entirely in the substrate 4 or for the most part in the
substrate 4.
The lower part 24 of the film cooling hole 28 comprises for example
a symmetry line 46 in longitudinal section.
The symmetry line 46 also constitutes for example an outflow
direction 46 for a coolant, which flows through the cooling hole
28.
A contour line 47, which extends parallel to the symmetry line 46
on the inner side of the film cooling hole 28 or represents a
projection of the symmetry line 46 onto the inner side of the lower
part 24 of the film cooling hole 28, makes an acute angle .alpha.1
with the outer surface 43, which is in particular 30.degree.+/-10%.
The film cooling hole 28 is thus inclined in the overflow direction
37.
The edge length a.sub.28 (FIG. 8) or the diameter .phi..sub.28 of
the film cooling hole 28 is for example about 0.62 mm or 0.7 mm for
a rotor blade and about 0.71 mm or 0.8 mm for guide vanes.
The contour line 47, which preferably extends parallel to the
outflow direction 46 along the contour 49 of the lower part 24,
makes an acute angle .alpha.2 with a diffuser line 48 which extends
on the inner face 50 of the appendage 14 of the diffuser 13, and
which represents a projection of the overflow direction 37 onto the
inner face 50 of the appendage 14 of the diffuser 13.
The angle .alpha.2 is in particular 10.degree.+/-10%.
Along the symmetry line 46, the lower part 24 has a constant cross
section which comprises in particular n-fold rotational symmetry
(square, rectangular, round, oval, . . . ).
The diffuser 13 is created by the cross-sectional area of the film
cooling hole 28 widening, i.e. being designed with a funnel shape
in cross section. The appendage 14 to the contour 49 does not
necessarily extend entirely around the outlet opening 58 of the
film cooling hole 28, rather only partially, in particular over
half or less of the circumference of the outlet opening 58.
The diffuser 13 is preferably arranged only--as seen in the
overflow direction 37 of the hot gas 22--in the rear region of the
opening 58 (FIG. 7). Side lines 38 of the diffuser 13 or of the
appendage 14 extend for example parallel to the overflow direction
37 in plan view (FIG. 7).
The overall layer thickness of the at least one layer 7, 10 is from
about 400 .mu.m to 700 .mu.m, in particular 600 .mu.m.
FIG. 8 shows another configuration of the film cooling hole 28 and
a plan view of the diffuser 13 in the plane of the outer surface 25
of the layer system or component 1.
The appendage 14 has, for example, a trapezoidal shape in the plane
of the outer surface 25.
In the plane of the surface 25, the appendage 14 of the diffuser 13
has a longitudinal length l.sub.1 of preferably about 3 mm in the
overflow direction 37.
The greatest width i.e. the greatest transverse length l.sub.2 of
the diffuser 13 in the surface, i.e. measured perpendicularly to
the overflow direction 37, preferably has a size of 2+-0.2 mm for
rotor blades and a size of 4+-0.2 mm for guide vanes, and is at
most 8 mm.
In the exemplary embodiment of FIG. 8, the widening of the diffuser
13 begins on a widening front edge 62, i.e. at the appendage 14,
and widens in the overflow direction 37.
The overflow direction 37 makes an acute angle .alpha.3, in
particular 10.degree.+/-10%, with a lateral delimiting line 38 of
the appendage 14 in the plane of the outer surface 25.
The diffuser 13 preferably widens departing from the contour 49 of
the lower part 24, which is for example symmetrical with respect to
two mutually perpendicular axes, transversely to the flow direction
37 in each case by an angle .alpha.3, which is in particular
10.degree.+/-10%, in which case the widening already begins on a
leading edge 61 (as seen in the overflow direction 37) of the film
cooling hole 28 and extends as far as the trailing edge 64.
The diffuser 13 therefore has a trapezoidal cross section in the
plane of the surface 25 (FIG. 9).
The diffuser 13 is produced by a material erosion method, for
example electron bombardment or laser irradiation. Only in this way
can a multiplicity of cooling holes be produced accurately and
reproduced.
FIGS. 10, 11, 12 and 13 show various contours of the film cooling
hole 28.
The lower part 24 of the film cooling hole 28 is designed to be
cuboid here, merely by way of example, although it may also have a
round or oval cross-sectional shape.
The diffuser 13 in FIG. 10 is lengthened for example only in the
overflow direction 37, so that the cross section of the outlet
opening 58 is greater than the cross section of the lower part 24.
The film cooling hole 28 thus corresponds to the film cooling hole
according to FIG. 2, 6 or 7.
Based on FIG. 10, FIG. 11 represents a film cooling hole 28 which
is also widened in the overflow direction 37 transversely to the
overflow direction 37, i.e. it corresponds to FIG. 8.
The diffuser 13 in FIG. 12 is lengthened for example only
transversely to the overflow direction 37, so that here again the
cross section of the outlet opening 58 is greater than the cross
section of the lower part 24.
The film cooling hole 28 consists for example of a cuboid lower
part 24, which is adjoined by a diffuser 13 in the form of a
hexahedron with parallel trapezoidal side faces.
The diffuser 13 in FIG. 13 is widened both only in the overflow
direction 37 and in both directions transversely to the overflow
direction 37.
FIGS. 6, 7, 8, 9, 10, 11 and 13 respectively show that the diffuser
13 is for the most part arranged behind the outlet opening 58, as
seen in the overflow direction 37.
This means that the diffuser 13 is formed by an asymmetric widening
as seen in the overflow direction 37. Uniform widening of the cross
section of the lower part 24 of the film cooling hole 28 at the
level of the outer surface 25 is not desired.
It can be seen clearly in FIG. 6, and is correspondingly described,
that the appendage 14 represents a widening of the cross section in
the overflow direction 37 so that the diffuser is formed. This is
also shown by the plan view of FIG. 6 according to FIG. 7.
In FIG. 8, the widening of the aperture of the cross section of the
film cooling hole in the overflow direction 37 begins from the line
62.
In FIG. 9, the widening of the diffuser 13 already begins on the
leading edge 61 as seen in the overflow direction 37.
Widening of the cross section of the film cooling hole 28 at the
level of the outer surface 25 against the flow direction 37, i.e.
before the leading edge 61, is not present or is present only to a
small extent compared with the widening of the cross section in the
overflow direction 37.
FIG. 14 shows a perspective view of a rotor blade 120 or guide vane
130 of a turbomachine, which extends along a longitudinal axis
121.
The turbomachine may be a gas turbine of an aircraft or of a power
plant for electricity generation, a steam turbine or a
compressor.
Successively along the longitudinal axis 121, the blade 120, 130
comprises a fastening region 400, a blade platform 403 adjacent
thereto and a blade surface 406.
As a guide vane 130, the vane 130 may have a further platform (not
shown) at its vane tip 415.
A blade root 183, which is used to fasten the rotor blades 120, 130
on a shaft or a disk (not shown), is formed in the fastening region
400.
The blade root 183 is configured, for example, as a hammerhead.
Other configurations as a firtree or dovetail root are
possible.
The blade 120, 130 comprises a leading edge 409 and a trailing edge
412 for a medium which flows past the blade surface 406.
In conventional blades 120, 130, for example, solid metallic
materials, in particular superalloys, are used in all regions 400,
403, 406 of the blade 120, 130.
Such superalloys are known, for example, from EP 1 204 776 B1, EP 1
306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; these
documents are part of the disclosure in respect of the chemical
composition of the alloy.
The blades 120, 130 may in this case be manufactured by a casting
method, also by means of directional solidification, by a forging
method, by a machining method or combinations thereof.
Workpieces with a monocrystalline structure or structures are used
as components for machines which are exposed to heavy mechanical,
thermal and/or chemical loads during operation.
Such monocrystalline workpieces are manufactured, for example, by
directional solidification from the melt. These are casting methods
in which the liquid metal alloy is solidified to form a
monocrystalline structure, i.e. to form the monocrystalline
workpieces, or directionally.
Dendritic crystals are in this case aligned along the heat flux and
form either a rod-crystalline grain structure (columnar, i.e.
grains which extend over the entire length of the workpiece and in
this case, according to general terminology usage, are referred to
as directionally solidified) or a monocrystalline structure, i.e.
the entire workpiece consists of a single crystal. It is necessary
to avoid the transition to globulitic (polycrystalline)
solidification in this method, since nondirectional growth will
necessarily form transverse and longitudinal grain boundaries which
negate the good properties of the directionally solidified or
monocrystalline component.
When directionally solidified structures are referred to in
general, this is intended to mean both single crystals which have
no grain boundaries or at most small-angle grain boundaries, and
also rod-crystal structures which, although they do have grain
boundaries extending in the longitudinal direction, do not have any
transverse grain boundaries. These latter crystalline structures
are also referred to as directionally solidified structures.
Such methods are known from U.S. Pat. No. 6,024,792 and EP 0 892
090 A1; these documents are part of the disclosure.
The blades 120, 130 may likewise comprise coatings against
corrosion or oxidation, for example (MCrAlX; M is at least one
element from the group iron (Fe), cobalt (Co), nickel (Ni), X is an
active element and stands for yttrium (Y) and/or silicon and/or at
least one rare-earth element, for example hafnium (Hf)). Such
alloys are known, for example, from EP 0 486 489 B1, EP 0 786 017
B1, EP 0 412 397 B1 or EP 1 306 454 A1, which are intended to be
part of this disclosure in respect of the chemical composition of
the alloy.
On the MCrAlX, there may also be a thermal insulation layer which
consists for example of ZrO.sub.2, Y.sub.2O.sub.3--ZrO.sub.2, i.e.
it is non-stabilized or partially or fully stabilized by yttrium
oxide and/or calcium oxide and/or magnesium oxide.
Rod-shaped grains are generated in the thermal insulation layer by
suitable coating methods, for example electron beam deposition
(EB-PVD).
Refurbishment means that components 120, 130 may need to have
protective layers removed from them after their use (for example by
sandblasting). Corrosion and/or oxidation layers or products are
then removed. Optionally, cracks in the component 120, 130 will
also be repaired. The component 120, 130 is then recoated and the
component 120, 130 is used again.
The blade 120, 130 may be designed to be a hollow or solid. If the
blade 120, 130 is intended to be cooled, it will be hollow and
optionally also comprise film cooling holes 418 (represented by
dashes).
FIG. 15 shows a combustion chamber 110 of a gas turbine 100. The
combustion chamber 110 is designed for example as a so-called ring
combustion chamber, in which a multiplicity of burners 107 arranged
in the circumferential direction around a rotation axis 102, which
produce flames 156, open into a common combustion chamber space
154. To this end, the combustion chamber 110 in its entirety is
designed as an annular structure which is positioned around the
rotation axis 102.
In order to achieve a comparatively high efficiency, the combustion
chamber 110 is designed for a relatively high temperature of the
working medium M, i.e. about 1000.degree. C. to 1600.degree. C. In
order to permit a comparatively long operating time even under
these operating parameters which are unfavorable for the materials,
the combustion chamber wall 153 is provided with an inner lining
formed by heat shield elements 155 on its side facing the working
medium M.
Each heat shield element 155 made of an alloy is equipped with a
particularly heat-resistant protective layer on the working medium
side (MCrAlX layer and/or ceramic coating), or is made of
refractory material (solid ceramic blocks).
These protective layers may be similar to the turbine blades, i.e.
for example MCrAlX means: M is at least one element from the group
iron (Fe), cobalt (Co), nickel (Ni), X is an active element and
stands for yttrium (Y) and/or silicon and/or at least one
rare-earth element, for example hafnium (Hf). Such alloys are
known, for example, from EP 0 486 489 B1, EP 0 786 017 B1, EP 0 412
397 B1 or EP 1 306 454 A1, which are intended to be part of this
disclosure in respect of the chemical composition of the alloy.
On the MCrAlX, there may also be an e.g. ceramic thermal insulation
layer which consists for example of ZrO.sub.2,
Y.sub.2O.sub.3--ZrO.sub.2, i.e. it is non-stabilized or partially
or fully stabilized by yttrium oxide and/or calcium oxide and/or
magnesium oxide.
Rod-shaped grains are generated in the thermal insulation layer by
suitable coating methods, for example electron beam deposition
(EB-PVD).
Refurbishment means that heat shield elements 155 may need to have
protective layers removed from them after their use (for example by
sandblasting). Corrosion and/or oxidation layers or products are
then removed. Optionally, cracks in the heat shield element 155
will also be repaired. The heat shield elements 155 are then
recoated and the heat shield elements 155 are used again.
Owing to the high temperatures inside the combustion chamber 110, a
cooling system is also provided for the heat shield elements 155 or
their holding elements. The heat shield elements 155 are then for
example hollow and optionally also comprise cooling holes (not
shown) opening into the combustion chamber space 154.
FIG. 16 shows by way of example a gas turbine 100 in a longitudinal
partial section.
The gas turbine 100 internally comprises a rotor 103, or turbine
rotor, mounted so that it can rotate about a rotation axis 102 and
having a shaft 101.
Successively along the rotor 103, there are an intake manifold 104,
a compressor 105, an e.g. toroidal combustion chamber 110, in
particular a ring combustion chamber, having a plurality of burners
107 arranged coaxially, a turbine 108 and the exhaust manifold
109.
The ring combustion chamber 110 communicates with an e.g. annular
hot gas channel 111. There, for example, four successively
connected turbine stages 112 form the turbine 108.
Each turbine stage 112 is for example formed by two blade rings. As
seen in the flow direction of a working medium 113, a row 125
formed by rotor blades 120 follows in the hot gas channel 111 of a
guide vane row 115.
The guide vanes 130 are fastened on the stator 143 while the rotor
blades 120 of a row 125 are fitted on the rotor 103, for example by
means of a turbine disk 133.
Coupled to the rotor 103, there is a generator or a work engine
(not shown).
During operation of the gas turbine 100, air 135 is taken in by the
compressor 105 through the intake manifold 104 and compressed. The
compressed air provided at the turbine-side end of the compressor
105 is delivered to the burners 107 and mixed there with a fuel.
The mixture is then burnt to form the working medium 113 in the
combustion chamber 110. From there, the working medium 113 flows
along the hot gas channel 111 past the guide vanes 130 and the
rotor blades 120. At the rotor blades 120, the working medium 113
expands by imparting momentum, so that the rotor blades 120 drive
the rotor 103 and the work engine coupled to it.
During operation of the gas turbine 100, the components exposed to
the hot working medium 113 experience thermal loads. Apart from the
heat shield elements lining the ring combustion chamber 110, the
guide vanes 130 and rotor blades 120 of the first turbine stage
112, as seen in the flow direction of the working medium 113, are
thermally loaded most greatly.
In order to withstand the temperatures prevailing there, they may
be cooled by means of a coolant.
The substrates may likewise comprise a directional structure, i.e.
they are monocrystalline (SX structure) or comprise only
longitudinally directed grains (DS).
Iron-, nickel- or cobalt-based superalloys, for example, are used
as material for the components, in particular for the turbine
blades and vanes 120, 130 and components of the combustion chamber
110.
Such superalloys are known, for example, from EP 1 204 776 B1, EP 1
306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949; these
documents are part of the disclosure in respect of the chemical
composition of the alloy.
The blades and vanes 120, 130 may likewise comprise coatings
against corrosion (MCrAlX; M is at least one element in the group
iron (Fe), cobalt (Co), nickel (Ni), X is an active element and
stands for yttrium (Y) and/or silicon, and/or at least one
rare-earth element or hafnium). Such alloys are known, for example,
from EP 0 486 489 B1, EP 0 786 017 B1, EP 0 412 397 B1 or EP 1 306
454 A1, which are intended to be part of this disclosure in respect
of the chemical composition of the alloy.
On the MCrAlX, there may also be a thermal insulation layer, which
consists for example of ZrO.sub.2, Y.sub.2O.sub.3--ZrO.sub.2, i.e.
it is non-stabilized or partially or fully stabilized by yttrium
oxide and/or calcium oxide and/or magnesium oxide.
Rod-shaped grains are generated in the thermal insulation layer by
suitable coating methods, for example electron beam deposition
(EB-PVD).
The guide vanes 130 comprise a guide vane root (not shown here)
facing the inner housing 138 of the turbine 108, and a guide vane
head lying opposite the guide vane root. The guide vane head faces
the rotor 103 and is fixed on a fastening ring 140 of the stator
143.
* * * * *